JPS5952573B2 - level shift circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse drive circuit that operates stably against DC bias power supply fluctuations and temperature fluctuations.

Generally, in a direct-coupled circuit in an integrated circuit, in order to obtain a large output signal, it is necessary to shift the DC level of the operating point.

Particularly in a pulse drive circuit, its output DC level must match the threshold level of the next stage.

FIG. 1 shows a conventional pulse drive circuit, in which transistors Q1. Q2, resistor R1, R2 diode D1, etc. constitute a pulse drive circuit section, and transistor Q3 constitutes a drive circuit.

Note that El and R2 are DC bias power supplies, and el is a signal source.

In the above circuit, current I flows through resistor R1 and diode D0.

is ■F; forward voltage of diode Therefore, the DC level shift amount Δ■ becomes.

Therefore, the voltage (4) at the output point A is as follows.

As can be seen from equation (3), the voltage VA at point A is E
It depends on l, R2, and VF.

On the other hand, the threshold level of transistor Q3 is V
However, in the above circuit, the DC level at point A is
I can't do it.

Therefore, the DC bias power supply E1. If E2 is not made sufficiently stable, fluctuations will occur in the output.

Also, the influence of temperature changes is relatively large.

The present invention was made in order to address the above-mentioned circumstances, and an object of the present invention is to provide a pulse drive circuit that can operate with sufficient stability against voltage fluctuations and temperature changes of a bias power supply and is suitable for integration into an integrated circuit. do.

Embodiments of the present invention will be described below with reference to the drawings.

The invention specifically aims to set the DC level to be level-shifted independently of the signal level.

In order to achieve this objective, the configuration is characterized in that the blood flow bias power supply E2 that energizes the signal source to be level shifted is used as a power supply that drives the level shift circuit itself.

That is, this circuit configuration has the effect that the amount to be level shifted can be set regardless of the signal from the signal source e1.

Furthermore, the present invention has a unique feature in that the effect of voltage fluctuations of the DC bias power supply that energizes both the signal source and the level shift circuit has no effect on the shifted DC voltage level. effective.

In FIG. 2, El is a first DC bias power supply, and R2 is a second DC bias power supply.

A second DC bias power supply R2 is supplied to the base of the transistor Qll, and an input signal e1 and a second DC bias power supply E are supplied to the base of the transistor Q12.
2 is supplied.

A first DC bias power supply E1 is supplied to the collectors of the transistors Q11+Q12.

The emitter of the I-transistor Q1□ is connected to the anode of the diode JDn+1 and the base of the 1-transistor Q13 through diodes JD1 to JDn as PN junction driving elements in series, and then through a resistor R1 in series.

The cathode of the diode JDn+1 is connected to the reference potential terminal, forming a current path on the emitter side of the transistor Q1□.

The emitter of the transistor Q1° is the diode KD1~
It is connected to the collector of transistor Q13 through KDm in series and then through resistor R1□ in series.

The emitter of this transistor Q13 is connected to the reference potential terminal, and forms a current mirror circuit together with the transistor Q1.

Also, the collector of the transistor Q
Connected to 14 bases.

The emitter of this transistor Q+4 is connected to the reference potential terminal.

According to the above circuit, a current I flows through the diodes JD1 to JDo+1 and the resistor R1.

is,■, ;forward voltage of diode R2; Voltage of power supply E2 becomes.

Transistor Q1□ forms a current mirror circuit with respect to transistor Qll, and diode KD1
~KDm and the current flowing through resistor R12.

Therefore, the level shift amount ΔV is as follows.

Therefore, the DC voltage level VA at the base of the transistor Q14 becomes: (1) F; Forward voltage R2 of the diode; Voltage of the second DC bias power supply E2.

Here, if R1-R2n=m, the equation (6) becomes, and the DC level of the base of the transistor Q14 becomes VF.

Inside the integrated circuit, the resistance ratio can be created with an accuracy within ±3%, so the condition R1□=R1□ can be fully satisfied.

On the other hand, the threshold level of transistor Q14 is also ■.

Therefore, according to this circuit, the output DC level remains constant even if the DC bias power supply fluctuates.

Furthermore, since the output DC level of the pulse drive section and the DC threshold level of the drive circuit section by the transistor Q14 in the next stage are both 2, it is possible to drive the next stage with sufficient stability even if the temperature changes.

Therefore, even when the human power signal level is low, the next stage can be driven with sufficient stability.

As explained above, the present invention can operate stably with respect to voltage fluctuations and temperature changes of a bias power supply, can operate stably even with a small input signal, and is a pulse drive suitable for integrated circuits. The circuit can be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional pulse drive circuit, and FIG. 2 is a circuit diagram of a pulse drive circuit according to an embodiment of the present invention. Q11-Q14...Transistor, R11-R
12...Resistance, D1 to Dn, Dn+1. D1～
Dm...Diode.

Claims (1)

[Claims] 1 a signal source generating a signal to be level shifted;
a first DC bias power supply that energizes the signal source; a first transistor to which an energizing voltage is applied to the base side by the first DC bias power supply; and a first transistor to which a signal from the signal source is applied to the base side. a second transistor;
a second DC bias power supply that energizes the transistor and the first transistor, and at least a PN junction drive element is disposed on the emitter side of the first transistor,
A first current path through which the current of this driving element flows;
A third current path whose base is biased according to the current path and the PN junction driving element and through which a current corresponding to the first current path flows.
an intervening connection to a current mirror circuit formed by the transistor, and a second current path formed by the collector of the third transistor constituting the current mirror circuit and the collector-emitter current path of the first transistor. a series circuit consisting of a resistor and a PN junction drive element;
A level shift circuit comprising: a resistor connected in series to the first current path.